“I could smell burning when I got off - I reckon they were trying to burn it.”

The eyewitness, who did not want to be named, said he did not believe the attack was racist or sectarian.

The 40-year-old, who moved to Northern Ireland from the Middle East 15 years ago, said he was badly shaken.

Police have appealed for information.

A PSNI spokesman said: “Just before 8.10pm, when the bus was stopped to pick up passengers, a male got on and told the driver not to let anyone else on. Following this, a number of other young males entered the bus and assaulted a male passenger. They also broke a window before getting off again.

“The assaulted male refused medical treatment and got off in the city centre.

“Anyone with any information about this incident is asked to contact Strandtown Police Station on the non emergency number 101. Or if someone would prefer to provide information without giving their details, they can contact the independent charity Crimestoppers and speak to them anonymously on 0800 555 111.”